Process for the production of ketones

ABSTRACT

A process for the production of aliphatic or alicyclic monoketones or alicyclic diketones of the formula R 1 —C(═O)—R 2  in which R 1  is a linear or branched C 1-10 -alkyl group and R 2  is a linear or branched C 1-10 -alkyl group or a phenyl group, or R 1  or R 2  together are —(CH 2 ) m —[C(═O)] n —(CH 2 ) p —, wherein m and p independently are integers from 1 to 4 and n is 0 or 1, thus forming an alicyclic ring together with the carbonyl group of R 1 —C(═O)—R 2  by oxidizing a secondary alcohol of formula R 1′ —CHOH—R 2′  in which R 1′  and R 2′  either have the same meaning as R 1  and R 2  above or, if R 1  and R 2  together are —(CH 2 ) m —[C(═O)] n —(CH 2 ) p —, are together —(CH 2 ) m —(CHOH) n —(CH 2 ) p — wherein m, n and p are as defined above, with a peroxy compound in the presence of a carboxylic acid and a manganese(IV) complex of 1,4,7-trimethyl-1,4,7-triazacyclononane.

This application is a 371 national stage application of International(PCT) Application No. PCT/EP02/04440, filed on Apr. 23, 2002, that haspriority benefit of European Patent Application No. 01111776.9 filed onMay 15, 2001, that has priority benefit of U.S. Provisional PatentApplication No. 60/286,539 filed on Apr. 27, 2001.

The invention relates to a process for the production of aliphatic andalicyclic ketones by oxidizing the corresponding secondary alcohols witha peroxy compound in the presence of a catalyst.

The ketones obtainable by the process of the invention have the generalformulaR¹—C(═O)—R²   (I)in which R¹ is a linear or branched C₁₋₁₀-alkyl group and R² is a linearor branched C₁₋₁₀-alkyl group or a phenyl group,

or R¹ and R² together are —(CH₂)_(m)—[C(═O)]_(n)—(CH₂)_(p)—, wherein mand p independently are integers from 1 to 4 and n is 0 or 1, thusforming an alicyclic ring together with the carbonyl group of (I).

These ketones are valuable compounds for a large number of applications,for example as solvents, building blocks for organic syntheses,fragrances etc.

Linear or branched C₁₋₁₀-alkyl groups are, for example, methyl, ethyl,propyl, isopropyl butyl, isobutyl, sec-butyl, tert-butyl pentyl,2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl,nonyl and decyl, including all isomers of these groups. The ketoneswherein R¹ and R² together are a group of the formula—(CH₂)_(m)—[C(═O)]_(n)—(CH₂)_(p)— are in particular all alicyclicmonoketones having 3 to 9 ring carbon atoms or diketones having 4 to 10carbon atoms wherein the carbonyl groups are separated by at least onemethylene group. These alicyclic ketones include cyclopropanone,cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone,cyclooctanone, cyclononanone, 1,3-cyclobutanedione,1,3-cyclopentanedione, 1,3-cyclohexanedione, 1,4-cyclohexanedione,1,3-cycloheptanedione, 1,4-cycloheptanedione, 1,3-cyclooctanedione,1,4-cyclooctanedione, 1,5-cyclooctanedione, 1,3-cyclononandione,1,4-cyclononanedione, 1,5-cyclononanedione, 1,3-cyclodecanedione,1,4-cyclodecanedione, 1,5-cyclodecanedione and 1,6-cyclodecanedione.

While some of the above mentioned ketones (I) are being produced by thechemical industry in large amounts (e. g. acetone, cyclohexanone) usingprocesses giving good yields, some others are only available by tediousprocedures and/or in poor yields. The object of the present inventionwas to provide a versatile process for the production of these ketonesin good yields and without expensive reactants.

According to the invention, this has been accomplished by the process ofclaim 1.

It has been found that secondary alcohols of the formulaR^(1′)—CHOH—R^(2′)  (II)in which R^(1′) and R^(2′) either have the same meaning as R¹ and R²above or, if R¹ and R² together are —(CH₂)_(m)—[C(═O)]_(n)—(CH₂)_(p)—(i.e., if the product is a alicyclic diketone), are together—(CH₂)_(m)—(CHOH)_(n)—(CH₂)_(p)— wherein m, n and p are as definedabove, can smoothly be oxidized by peroxy compounds in the presence of acarboxylic acid and a manganese(IV) complex of1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃tacn) to give thecorresponding ketones (I) in good to excellent yields.

Preferred peroxy compounds are hydrogen peroxide and peroxycarboxylicacids and mixtures thereof. It should be noted that hydrogen peroxidereacts with carboxylic acids to give peroxycarboxylic acids in anequilibrium reaction.

It is also possible to use other peroxy compounds, for example,tert-butyl hydroperoxide.

The most preferred carboxylic acid is acetic acid.

The preferred manganese(IV) complex of Me₃tacn is the dinuclear complex[(Me₃tacn)₂Mn₂O₃]²⁺[PF6]₂ ⁻ with three bridging oxo ligands[=tri-μ-oxobis(1,4,7-trimethyl-1,4,7-triazacyclononane)dimanganesebis(hexafluorophosphate)] which has been described by K. Wieghardt etal., J. Am. Chem. Soc. 1988, 110, 7398.

The process according to the invention may be carried out in polaraprotic solvents such as acetonitrile, nitromethane or mixtures thereof,acetonitrile being especially preferred.

A particularly preferred application of the process of this invention isthe production of 1,4-cyclohexanedione (I;R¹,R²═—(CH₂)_(m)—[C(═O)]_(n)—(CH₂)_(p)—, m=p=2, n=1) from1,4-cyclohexanediol (II; R^(1′),R^(2′)═—(CH₂)_(m)—(CHOH)_(n)—(CH₂)_(p)—,m=p=2, n=1) which is easily available from hydroquinone.

The process of the invention may be carried out at or near roomtemperature, e. g., at 0-40° C., the reaction times being typically afew hours or less. The work-up can be done according to methods wellknown in the art, preferably after addition of a suitable reducing agentto destroy any excess of peroxy compound in order to avoid furtheroxidation and potential explosion hazards.

The invention is illustrated by the following non-limiting examples.

EXAMPLE 1 Preparation of 1,4-Cyclohexanedione

To a solution of 0.5 g of 1,4-cyclohexanediol in 10 ml of acetonitrilewere added 0.2 ml of a 6.32 mM acetonitrile solution of[(Me₃tacn)₂Mn₂O₃][PF₆]₂ and 0.4 ml of acetic acid (99%). A mixture of 2ml of a 35% aqueous hydrogen peroxide solution in 11 ml of acetonitrilewas added dropwise under vigorous sting at 23° C. within one hour. Afterthe addition the clear solution was stirred for additional 30 minutes,all volatiles removed in vacuo and the residue analysed by gaschromatography, ¹H- and ¹³C NMR spectroscopy, showing >99% conversionand >99% selectivity. The analyses were compared with a commerciallyavailable (Fluka) sample of 1,4-cyclohexanedione.

EXAMPLES 2-9

In a procedure similar to that of example 1, several secondary alcoholswere oxidized In each case, a reaction mixture containing 0.23 M (1 M=1mol/l) of the respective alcohol, 1.0 M of hydrogen peroxide, 0.4×10⁻⁴ Mof [(Me₃tacn)₂Mn₂O₃][PF₆]₂ and 0.5 M of acetic acid in acetonitrile assolvent was reacted at 20° C. for 3 h. The yields of the products weremeasured by gas chromatography after treatment of the samples withtriphenylphosphine. The results are given in Table 1. All yields arebased on the initial amounts of alcohol.

TABLE 1 Con- Exam- version Yield ple Alcohol [%] Product [%] 22-propanol 100 acetone 98 3 2-butanol 100 2-butanone 98 4 2-pentanol 992-pentanone 97 5 3-pentaaol 98 3-pentanone 97 6 3-methyl-2- 1003-methyl-2- 100 butanol pentanone 7 3-hexanol 97 3-hexanone 96 8cyclohexanol 95 cyclohexanone 91 9 1-phenylethanol ≈100   acetophenone≈100  

1. A process for the production of an aliphatic or alicyclic monoketoneor an alicyclic diketone of the formula:R¹—C(═O)—R²  (I) in which R¹ is a linear or branched C₁₋₁₀-alkyl, and R²is a linear or branched C₁₋₁₀-alkyl or a phenyl, or R¹ or R² togetherare —(CH₂)_(m)—[C(═O)]_(n)—(CH₂)_(p)—, wherein m and p independently areintegers from 1 to 4 and n is 0 or 1, thus forming an alicyclic ringtogether with the carbonyl group of (I), by oxidizing a secondaryalcohol of formulaR^(1′)—CHOH—R^(2′)  (II) in which R^(1′) and R^(2′) either have the samemeaning as R¹ and R² above or, if R¹ and R² together are—(CH₂)_(m)—[C(═O)]_(n)—(CH₂)_(p)—, are together—(CH₂)_(m)—(CHOH)_(n)—(CH₂)_(p)— wherein m, n and p are as definedabove, with a peroxy compound in the presence of a carboxylic acid and amanganese(IV) complex of 1,4,7-trimethyl-1,4,7-triazacyclononane.
 2. Theprocess of claim 1 wherein the peroxy compound is selected from thegroup consisting of hydrogen peroxide and peroxycarboxylic acids andmixtures thereof.
 3. The process of claim 1 wherein the carboxylic acidis acetic acid.
 4. The process of claim 1 wherein the manganese(IV)complex of 1,4,7-trimethyl-1,4,7-triazacyclononane istri-μ-oxobis(1,4,7-trimethyl-1,4,7-triazacyclononane)-dimanganesebis(hexafluorophosphate).
 5. The process of claim 1 wherein theoxidation is conducted in a solvent selected from the group consistingof acetonitrile, nitromethane, and mixtures thereof.
 6. The process ofclaim 1 wherein R¹ and R² together are —(CH₂)₂—C(═O)—(CH₂)₂— and R^(1′)and R^(2′) together are —(CH₂)₂—CHOH—(CH₂)₂—.
 7. The process of claim 2wherein the carboxylic acid is acetic acid.
 8. The process of claim 2wherein the manganese(IV) complex of1,4,7-trimethyl-1,4,7-triazacyclononane istri-μ-oxobis(1,4,7-trimethyl-1,4,7-triazacyclononane)-dimanganesebis(hexafluorophosphate).
 9. The process of claim 3 wherein themanganese(IV) complex of 1,4,7-trimethyl-1,4,7-triazacyclononane istri-μ-oxobis(1,4,7-trimethyl-1,4,7-triazacyclononane)-dimanganesebis(hexafluorophosphate).
 10. The process of claim 2 wherein theoxidation is conducted in a solvent selected from the group consistingof acetonitrile, nitromethane, and mixtures thereof.
 11. The process ofclaim 3 wherein the oxidation is conducted in a solvent selected fromthe group consisting of acetonitrile, nitromethane, and mixturesthereof.
 12. The process of claim 4 wherein the oxidation is conductedin a solvent selected from the group consisting of acetonitrile,nitromethane, and mixtures thereof.
 13. The process of claim 2 whereinR¹ and R² together are —(CH₂)₂—C(═O)—(CH₂)₂— and R^(1′) and R^(2′)together are —(CH₂)₂—CHOH—(CH₂)₂—.
 14. The process of claim 3 wherein R¹and R² together are —(CH₂)₂—C(═O)—(CH₂)₂— and R^(1′) and R^(2′) togetherare —(CH₂)₂—CHOH—(CH₂)₂—.
 15. The process of claim 4 wherein R¹ and R²together are —(CH₂)₂—C(═O)—(CH₂)₂— and R^(1′) and R^(2′) together are—(CH₂)₂—CHOH—(CH₂)₂—.
 16. The process of claim 5 wherein R¹ and R²together are —(CH₂)₂—C(═O)—(CH₂)₂— and R^(1′) and R^(2′) together are—(CH₂)₂—CHOH—(CH₂)₂—.
 17. The process of claim 1 wherein R^(2‘)isphenyl.
 18. The process of claim 4 wherein the carboxylic acid is aceticacid, the peroxy compound is hydrogen peroxide, the secondary alcohol isa cyclohexanediol and the oxidation is conducted in acetonitrile. 19.The process of claim 18 wherein the cyclohexanediol is1,4-cyclohexanediol.
 20. The process of claim 1 wherein the secondaryalcohol is cyclohexanediol.
 21. The process of claim 1 wherein R^(1″)isa linear or branched C₁₋₁₀-alkyl and R^(2″)is a linear or branchedC₁₋₁₀-alkyl.
 22. The process of claim 1 wherein the oxidation isconducted in a polar aprotic solvent.
 23. The process of claim 22wherein the polar aprotic solvent is acetonitrile.
 24. The process ofclaim 1 wherein the oxidation is conducted at 0 to 40 °C.
 25. Theprocess of claim 1 wherein, after the oxidation has been conducted, areducing agent is added to reduce any excess of the peroxide compound.